TOTO TSU48 Unifit Rough-In



What is a Rough-in?

Unless you plan to replace your toilet, it is unlikely you have ever thought about a toilet’s rough-in. But if you are, understanding what a rough-in is and learning how to measure your toilet’s rough-in distance is of the utmost importance.

The toilet rough-in, generally measured in inches in the United States, is the distance between the back of the bathroom’s finished wall and the center of the toilet drainpipe’s opening, which usually has a plastic or cast iron lining, called the flange. There is typically a wax ring around it. If you mismeasure this distance, your new toilet may not fit correctly, or there will be too much space between the toilet and the back wall of the bathroom.

The standard (or at least most common) toilet rough-in distance today is 12 inches. However, older homes, and even modern homes, may come with 10” or 14” rough-in distances depending on the size and shape of the bathroom. For example, a 10” rough-in is more common for smaller apartment bathrooms or powder rooms. Either way, it is best not to assume and to determine the distance with a tape measure.

How to measure your rough-in distance:

  1. If the toilet has been removed, identify the drainpipe on the floor. The hole will typically have a plastic or cast iron lining called the flange.
  2. Measure the distance from the back of the bathroom’s finished wall to the center (not base) of the toilet drain pipe/flange.
  3. If the toilet is still installed, measure the distance between the back finished wall and the center of one of the toilet’s mounting bolts.
  4. The distance should be close to 10”, 12”, or 14”. If not, measure again. All toilets have specifications that tell you the rough-in measurement.

How to measure a toilet’s rough-in distance (“RI” stands for Rough-in)